Ubuntu is wireless proof while Lubuntu isn't

Hello,

I've tried on 2 different laptops to connect the wifi. On both machines, it worked with Ubuntu 12.04 live CD AND Ubuntu 12.04 installation while it failed with Lubuntu 12.04 live CD AND Lubuntu 12.04 installation.

What can be done on a fresh Lubuntu install to get the equivalent of Ubuntu as far as wireless connection is concerned ?